A detailed description is given of myocardial ultrastructural changes in the various types of cardiomyopathies, including: hypertrophic cardiomyopathy, idiopathic ventricular dilated cardiomyopathy, histiocytoid cardiomyopathy, anthracycline-induced cardiomyopathy, the syndromes of endomyocardial disease and hyperosinophilia, and various infiltrative cardiomyopathies.